Electricity is a primary energy source used in residential and commercial applications. Determining electricity use is important for managing electricity distribution networks (e.g. power grids). Server clusters for example, which are also known as data centers and colloquially as “server farms”, consume vast amounts of electricity. A server cluster is a collection of computing resources typically including a number of server computers, network routers and switches maintained at a common facility. Server clusters are used for applications such as web hosting, off-site data storage, cluster computing, and cloud computing. Server clusters also serve as the physical architecture for search engines and data exchanges for email and data services.
Electricity to server clusters is generally supplied as alternating current over power lines. The power lines are connected to a facility housing the server computers and associated supporting devices. Within a facility, the electricity is typically supplied to one or more distribution circuits through a fuse box or respective circuit breakers. One or more power distribution units (PDUs) are coupled to each distribution circuit. A PDU typically includes one electrical input for receiving electricity, and two or more electrical outputs for providing electricity to other devices. Typically a number of server computers or other current drawing devices are coupled to each PDU in order to receive electricity.